The objective of this research is to study how state Medicaid policies affected smoking status during pregnancy, use of smoking cessation services during pregnancy, and infant health outcomes in the U.S. between 2000 and 2010. Tobacco use during pregnancy remains one of the most important modifiable causes of poor maternal and infant health outcomes, and women enrolled in Medicaid have more than twice the prenatal smoking prevalence of women enrolled in private insurance. Pregnancy presents an opportunity to intervene to promote smoking cessation, and in recent years, states have taken steps to promote Medicaid enrollment early in pregnancy and to improve coverage of smoking cessation services in Medicaid. Little is known, however, about how these changes to enrollment or service-delivery policies in state Medicaid programs have affected prenatal smoking status and infant health outcomes. Using data from the National Ambulatory Medical Care Survey, Aim 1 of the research will describe use of counseling and pharmacotherapy for smoking cessation during pregnancy among Medicaid- enrolled women nationally. Aim 2, using data from the Pregnancy Risk Assessment Monitoring System from 37 sites, will evaluate the effects of two optional state Medicaid enrollment policies to promote early initiation of prenatal care on smoking status during pregnancy and birth outcomes. Aim 2 will also investigate whether the effects of these enrollment policies are modified by the comprehensiveness of states' coverage of smoking cessation services. Aim 3, using administrative data from a Medicaid managed-care organization, will examine whether intensity of use of smoking cessation services changes over subsequent pregnancies among women enrolled in Medicaid who smoked during their first pregnancy, and if the presence of smoking-related complications in the first pregnancy is predictive of increased use of smoking cessation services. Research findings will provide evidence about how enrollment and service- delivery polices in state Medicaid programs can best promote smoking cessation during prenatal care. During the two-year award, Ms. Jarlenski will complete coursework in data management, tobacco control, and epidemiology; pursue research and publication opportunities with faculty mentors; and complete this dissertation research project. The research and training experiences will enable Ms. Jarlenski to achieve her career goal of becoming an independent investigator conducting innovative research to reduce tobacco use during pregnancy in the Medicaid population.